Author Topic: Thoughts of tuning mk5 GTI  (Read 955 times)

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Offline ch0005649

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Thoughts of tuning mk5 GTI
« on: June 17, 2020, 11:48:12 am »
Hello everyone, this is the first time I put some words on this forum. :D
I hope I can help guys who are thinking to tune their Rabbit. ;)
I've done tons of research including reading other forums, asking mechanics, watching the data thru the VCDS.
to sum up, I've done these mods by timeline below:

CTS cold air intake (Dec, 2018)
CTS PCV delete kit (Jan, 2019)
Resonator delete (June, 2019)
COBY resonator medium length (Oct,2019)
Aliexpress cheapo downpipe (Catless) (Dec, 2019)
NZ performance tuning stageII (Jan, 2020)
GFB DV+ (Feb, 2020)
OEM PCV kit (June, 2020)

each mods were all considered seriously and some of them are regretful.

1. CTS cold air intake
    I've searched on the internet to see what would be the most essential mods for mk5 gti. And they say the intake is a good one for the cool compressor spooling sound, pressure release noise, and also a good preparation for the tuning plan in the future. Furthermore, I could get rid of the stupid engine cover that it need to be removed(not as easy as pulling off) just to check things under the cover. I do not regret this mod. a must do mod.

Performance: no change (only if ecu remapped)
Sound: (compressor spooling sound, Diverter valve pressure release sound) x10 louder than stock


2. CTS PCV delete kit
    this mod was done right after a few months I purchased my gti. I was having issue of rough idle on this car and visited the tune shop in Henderson. they found the problem in 5 mins and said you might want the PCV delete to prevent the issue for ever. Since the PCV delete kit has no mechanical structure(blocked all valves except the hole for the oil filter) and it's made my aluminum. The only cons of PCV delete was emission when it's stock(which VAG guys care emission?). On this stage, problem solved.

Performance: no change
Sound: no change


3. Resonator delete
    this mod was the most regretful one. Indeed it's cool that the crackle and poping sound is loud enough to hear in your seats. And crackles are damn awesome in public car parks, but the cold start is kind of harsh to hear. It is loud as neighbors would hate you, and your girlfriend would not like the drone noise coming from bottom. Well.....I didn't care since I didn't have a girlfriend. >:D

Performance: no change
Sound: middle, low tone louder. strong drone. crackles and pops


4. COBY resonator medium length
    after driving for a few months, I realized that I'm kinda a pathetic ricer that there was no any performance improvement but only the noise. So I decided to set goal for stage II tune, needed a downpipe, ecu remap. However, the resonator delete is already loud enough and didn't want to be a more "ricer". A thicker DP produces louder and more aggressive sound is a common knowledge. So I had to find someone to weld the resonator back for me. The COBY (NZ brand) was a nice one that it's a straight type resonator unlike the factory one was chamber type, which means better flow in the exhaust. And not that quiet like the factory one(about 60% quite). I could still hear the crackle but no drone and no gross cold start. the resonator was $120. good mod IMO.

Performance: no change
Sound: no drone, but crackle and pops still alive


5. Aliexpress cheapo downpipe(Catless)
    This one was the funniest one. Those branded downpipes such as CTS, Miltek, Unitronic are like $1000 bucks and I didn't really want to spent that much. and I've heard the material itself is not that different between them. the biggest diff was the accuracy of the shape. I purchased the Chinese DP from Aliexpress for about $150+tax+shipment = $270.
    Then I brought the DP to a random local muffler shop to fit them. They said because it's a cheap one, it might not fit easily while they had experience that miltek fits perfectly and cheap one needs to be heated and re-shape it. So you will see the labour increasing. After all, they spent about 2.5 hours to heat it and twist it & cut and weld some part of the DP. I kinda feel sorry for them. cuz only their boss is getting most of the money. As a result, the DP is working really well until now. no gas leaks, no rust. I guess the material itself really doesn't make so much difference than expensive ones. totally costed me no more than $500

    Performance: no change (only if ecu remapped)
Sound: loud as resonator delete again but not that rough. drone a little in an acceptable range. crackle and pops even stronger. turbine spooling sound able to hear outside.


6. NZ performance tuning stageII
    I had driven the car for a month without a tune and of course CEL showed up. I prepared some money during the Christmas and was waiting for the tune shop to start their business after their holidays. To sum up first, ECU tune is a MUST MUST MUST do mod for the mk5 gti. every generation of GTI is getting faster now. mk7 is making 380nm torque stock while I had to tune it to reach it. Anyway, it is a big change. torque coming from 4000rpm is incomparable than stock. It totally got about 120nm torque improvement.
and to boost pressure is reading 22psi from the gauge. But it is true it makes some turbo lag now.

Performance: Massive
Sound: a little more aggressive


7. GFB DV+
    OK....the factory revision C diverter valve was failing, making whispering noise in full throttle. that means boost leak. Perhaps the rubber couldn't resist the boost pressure of stg 2. So I've heard some pros and cons of DV+. I would sum up both effects.
Pros:
made by aluminum (last forever unless your turbo explode)
holds boost better (official website says up to 50 psi)
the "optional spring" will make it hold minor boost right after releasing throttle (better shifting experience or re-acceleration).
Cons:
It needs to be lubricated by every oil change. (mk5 dv valve is under the car while mk6,7 are on the hood and easy)
The aluminum is solid, but the O ring and rubber parts are not. they need to be replaced someday

I have try without the spring at first and now fitted with the spring.
Performance: no change
Sound: with spring: appropriate release sound
           without spring: excessive air noise 


7. GFB DV+
 
Important
Do not use PCV delete if you are tuning your car
    it is not about emission. only black smoke and smell is coming out randomly. that not a big deal.
the problem came after a few months the car was tuned.
Engine oil starts leaking from the oil fill cap. and there were vapor coming out when I open the cap after a drive.
With tons of research, I found out that the block plate of the PCV delete was blocking air passing through the crankcase so it's making pressure in the crankcase. And that pressure is pushing oil out of the cap! Not only the oil leaking is the problem. the continuous pressure in the crankcase might damage the engine. Like mine, it was misfiring during cold start and red light.
but after the OEM PCV re-installation, all problem solved.

Performance: no change
Sound: no change 


These are the knowledge I have found in the internet and experiences myself.
some of them are trail and error
but this car is a really fun car to play with it's drive-ability and mechanical.
« Last Edit: June 17, 2020, 02:52:41 pm by ch0005649 »
2006 Golf mk5 GTI
stage 2 (NZ performance tuning)
aliexpress cheapo downpipe (no CAT)
COBY resonator
CTS intake
CTS PCV kit

Offline The Red Warrior

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  • Posts: 451
Re: Thoughts of tuning mk5 GTI
« Reply #1 on: June 18, 2020, 08:14:22 pm »
Nice write up.  :)
My Mk5 is APR stage 2+. Iím running a CTS Tuning downpipe (sourced from Glidn on this forum). I deleted the suitcase muffler at one point for a few weeks and then put it back on. Goodness knows why I did it in the first place as I donít actually want a noisy car.
Do you plan on doing any handling mods now that youíve got increased power?

Offline ch0005649

  • Posts: 7
Re: Thoughts of tuning mk5 GTI
« Reply #2 on: June 22, 2020, 11:17:57 am »
Nice write up.  :)
My Mk5 is APR stage 2+. Iím running a CTS Tuning downpipe (sourced from Glidn on this forum). I deleted the suitcase muffler at one point for a few weeks and then put it back on. Goodness knows why I did it in the first place as I donít actually want a noisy car.
Do you plan on doing any handling mods now that youíve got increased power?

yeah German vehicles are kinda noisy when they are resonator or muffler deleted. I was told by a guy who's working in a muffler shop.
I think we should never "straight-pipe" any cars unless they are just as fast as a real race car. I mean cars we could see on WRC, GT races. Otherwise it looks quite funny when it makes the same volume like a race car but moves so slow. People won't be pleasured by our "riced" car sound.

I am thinking about steering wheel for better grip. And since I'm not so wealthy, I do not consider any suspension related works on my GTI. It's even more expensive than the tune to replace some coil lovers or alloy wheels.
But I do think of Brakes. It's even hard to stop the car now lol. Too small. perhaps brake units from a wrecked R32 will work fine.
« Last Edit: June 22, 2020, 11:22:42 am by ch0005649 »
2006 Golf mk5 GTI
stage 2 (NZ performance tuning)
aliexpress cheapo downpipe (no CAT)
COBY resonator
CTS intake
CTS PCV kit

Offline The Red Warrior

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  • Posts: 451
Re: Thoughts of tuning mk5 GTI
« Reply #3 on: June 22, 2020, 02:18:50 pm »
Iíve changed to the multi function steering wheel from a Mk6 GTI. Itís a lot nicer than the Mk5 plus my original wheel wasnít a multi function one.
I also upgraded the brakes. I went with the NQSBBK. It uses the original discs but uses the 4 pot calipers from a Porsche Boxster. The feel is the same normally, but when slowing from high speed you can feel there is plenty more in reserve. Decent tyres are needed though.

Offline ch0005649

  • Posts: 7
Re: Thoughts of tuning mk5 GTI
« Reply #4 on: June 22, 2020, 03:32:56 pm »
Iíve changed to the multi function steering wheel from a Mk6 GTI. Itís a lot nicer than the Mk5 plus my original wheel wasnít a multi function one.
I also upgraded the brakes. I went with the NQSBBK. It uses the original discs but uses the 4 pot calipers from a Porsche Boxster. The feel is the same normally, but when slowing from high speed you can feel there is plenty more in reserve. Decent tyres are needed though.

oh that sounds nice for the mk6 steering wheel, does the buttons work?

I'm thinking those blue calipers from R32 will look very nice for my blue GTI, or do you think it would look like a smurf?

And I'm now using Bridgestone Potenza re003 at the front wheels.
It does a good job for faster corner driving. But still pointless for low speed acceleration with a FWD. wheel spin like hell. And performance tyres decrease our fuel consumption and comfort. And it lasts only about 25k kms. Need to fit on cheaper one next time. :-\ the only answer is AWD or well tuned RWD I presume.
2006 Golf mk5 GTI
stage 2 (NZ performance tuning)
aliexpress cheapo downpipe (no CAT)
COBY resonator
CTS intake
CTS PCV kit

Offline The Red Warrior

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  • Posts: 451
Re: Thoughts of tuning mk5 GTI
« Reply #5 on: June 22, 2020, 06:06:23 pm »
All buttons work except the left/right buttons on the RHS as I donít have the full height (Highline) multi function display. Itís nice having the button that acts as the ĎAsk Sirií function which links to the upgraded stereo with CarPlay.

I donít think the calipapers will look out of place so long as the blues match. My Porsche calipers are red (as is my car) but then GTI calipers are red in the first place.

I donít get any wheel spin now unless I dump the clutch and donít manage to throttle. I used to get a lot along with lots of tramping but not now. However, thatís after changing to coil overs, dogbone insert, aftermarket pendulum mount, front wishbone anti lift kit and mostly an LSD.
« Last Edit: June 22, 2020, 06:09:53 pm by The Red Warrior »

Offline ch0005649

  • Posts: 7
Re: Thoughts of tuning mk5 GTI
« Reply #6 on: June 23, 2020, 12:56:49 pm »
All buttons work except the left/right buttons on the RHS as I donít have the full height (Highline) multi function display. Itís nice having the button that acts as the ĎAsk Sirií function which links to the upgraded stereo with CarPlay.

I donít think the calipapers will look out of place so long as the blues match. My Porsche calipers are red (as is my car) but then GTI calipers are red in the first place.

I donít get any wheel spin now unless I dump the clutch and donít manage to throttle. I used to get a lot along with lots of tramping but not now. However, thatís after changing to coil overs, dogbone insert, aftermarket pendulum mount, front wishbone anti lift kit and mostly an LSD.
Oh that sounds nice.....how much about did you spend on those kits?
« Last Edit: June 23, 2020, 01:10:38 pm by ch0005649 »
2006 Golf mk5 GTI
stage 2 (NZ performance tuning)
aliexpress cheapo downpipe (no CAT)
COBY resonator
CTS intake
CTS PCV kit

Offline The Red Warrior

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  • Posts: 451
Re: Thoughts of tuning mk5 GTI
« Reply #7 on: June 23, 2020, 05:47:21 pm »
Ummm, only going by memory here so...
Bilstein B12 coilovers, $350 used. But then had to get cert as well.
Anti lift kit $250?
LSD $750
Pendulum mount, dunno. Check out the one by ECS Tuning as that what I bought.
Dogbone insert, $50?

All done over a few years though. And everything installed myself so that cuts down the cost considerably. Havenít done any performance mods in ages. Just interior stuff and daily driving really.

But if I had to pick the two best mods then thatís easy. Stage 1 tune (not that Iím on stage 1 anymore) and the Mk6 steering wheel.

Offline ch0005649

  • Posts: 7
Re: Thoughts of tuning mk5 GTI
« Reply #8 on: June 24, 2020, 10:57:10 am »
I would like to fit on the Dogbone for the wheel hops. any recommended brands?
steering wheel perhaps not for me.... :-\

anything you think has the best value for tyre grip?
2006 Golf mk5 GTI
stage 2 (NZ performance tuning)
aliexpress cheapo downpipe (no CAT)
COBY resonator
CTS intake
CTS PCV kit

Offline GLIDN

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Re: Thoughts of tuning mk5 GTI
« Reply #9 on: June 24, 2020, 11:34:31 am »
I would like to fit on the Dogbone for the wheel hops. any recommended brands?
steering wheel perhaps not for me.... :-\

anything you think has the best value for tire grip?

for Grip
get an anti-lift kit, and upgrade engine mounts with dogbone insert.

As for tires, switch to Michelin PS4. Huge improvement over the RE003. Less wheelspin too.
Audi A4 DTM - Stock NZ New | All servicing done | Carbon Clean done
Gone - VW Tiguan | APR Stage 1 | Stage 2 DSG | Tuned by HSP Tuning

Offline ch0005649

  • Posts: 7
Re: Thoughts of tuning mk5 GTI
« Reply #10 on: June 25, 2020, 04:43:34 pm »
for Grip
get an anti-lift kit, and upgrade engine mounts with dogbone insert.

As for tires, switch to Michelin PS4. Huge improvement over the RE003. Less wheelspin too.

Thanks for the inputs!
2006 Golf mk5 GTI
stage 2 (NZ performance tuning)
aliexpress cheapo downpipe (no CAT)
COBY resonator
CTS intake
CTS PCV kit